The Pointing Dance

This week, I have been engaged in an important, albeit tedious activity at the WIYN 3.5-meter telescope. I have been building pointing maps. Telescopes are large, bulky machines that have to point with extreme precision and track the almost literal clockwork motion of the sky. They are engineered carefully, but like any machine they are subject to wear and tear. What’s more, to keep getting the best science, telescopes have to be upgraded from time to time. This changes the telescope’s behavior with time.

The WIYN Telescope ready for a night of collecting pointing data

Because the Earth turns constantly, the sky overhead appears to move at a constant rate. To keep objects in the telescope’s field of view, the earliest telescopes were literally mounted to clocks that moved at the sky’s rate. To make these work, you have to imagine a line in the sky that’s a projection of the Earth’s equator. Then you have to tilt your tracking axis to be at the same angle as that imaginary line in the sky. Another way to think about it is that here at Kitt Peak National Observatory, we’re at 32 degrees north latitude, so you have to tilt your telescope 32 degrees up from the southern horizon to track the sky.

Now, if you look at the photo of the WIYN Telescope above, you’ll notice that it’s mounted flat to the floor and it’s not tipped to match our latitude. That’s because it’s expensive to engineer big heavy telescopes so they can be tipped up at an angle. So, the WIYN telescope actually has to track the sky in two axes: azimuth and elevation, kind of like a radar mount. To track the sky, we have to use computers to adjust the tracking rates constantly. The computers only know how fast to track in each axis if they know where we’re pointing in the sky. If there’s an error in pointing, there’s also an error in tracking.

When I tell people I’m a writer and an astronomer who operates telescopes, it’s often assumed that I have lots of free time on quiet nights at the telescope to write. That doesn’t happen on nights of pointing maps. Instead, it’s a busy night of pointing to a star, noting how far off it was from where we expected it and then moving on again. We do this for anywhere from 75 to 100 stars with a telescope like WIYN and the exercise takes about half the night.

The way pointing and tracking are interconnected also make me think of how I use outlines as a writer. With the telescope, we can imagine that I point to a star and correct the pointing at one spot, then let the telescope track. If the computer thinks the star will be a different point in an hour than it really will be, it will track toward that different point and it won’t follow the star. You need to know where the star really will be in an hour.

For me, an outline is like a little like a pointing map. It tells me where the plot is at point A and it tells me where I want to be once I reach point B. With the telescope, it better be pointed at the star at both points A and B. An outline is more flexible. It’s more like a guideline. I try to listen to my characters when I write my outlines and make sure that points A and B make sense for them. However, sometimes as I write, I find characters do things I didn’t quite imagine the first time. The beauty of an outline is I can change point B. The challenge is that when I do, I realize I may also have to change points C, D, and E as the plot progresses!

I’ve been having a lot of fun rewriting my novel, The Pirates of Sufiro for its 25th anniversary release. I actually wrote some of the original draft when the WIYN telescope was first being built in the 1990s. Rewriting the book is the ultimate case of writing to an outline, especially since I don’t want to change it so much that people can’t pick up older editions of the sequels and follow them. I’m expanding the story and letting my characters breathe more. I’m letting them guide me and asking if what they did entirely made sense for those characters. I’m taking them from point A to point B. Those points can’t really deviate, but I do allow myself to add points A.1, A.2, and A.3 to better explain how they moved from point A to point B.

You can read chapters from the previous edition and see how I’m following my version of a “pointing map” by following me Patreon. My site is at:

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